JPH0790686B2 - Shock absorber control device - Google Patents

Description

The present invention relates to a shock absorber control device that drives a damping force switching member according to a running state of a vehicle to adjust the damping force of a shock absorber.

In general, when a vehicle such as an automobile turns, a rolling phenomenon may occur, and especially when turning suddenly, the frequency of occurrence increases.

By the way, a shock absorber control device has been proposed in which the damping force of the shock absorber is automatically switched according to the traveling state of the vehicle in order to maintain a good traveling feeling of the vehicle even when traveling on a rough road. .

The present invention, in this type of shock absorber control device, detects a turning at which the rolling phenomenon occurs, and when it detects the turning, the damping force of the shock absorber is increased. It is an object of the present invention to provide a shock absorber control device capable of quickly and surely detecting a state in which a rolling phenomenon is likely to occur, and suppressing the occurrence of a rolling phenomenon.

Therefore, according to the present invention, as shown in FIG. 1, in the shock absorber control device that drives the damping force switching member a according to the running state of the vehicle to adjust the damping force of the shock absorber b, the right wheel that detects the speed of the right wheel is detected. The wheel speed sensor c, the left wheel speed sensor d for detecting the speed of the left wheel, and the temporal change amount of the wheel speed difference between the right wheel and the left wheel based on the detected right wheel speed and left wheel speed. The first means e for calculating and the second means f for comparing the change amount calculated by the first means e with a predetermined value are provided, and when the change amount exceeds the predetermined value, the attenuation is performed. A control device g that outputs a drive signal corresponding to the damping force switching member a so that the force is switched to a large state.

According to the shock absorber control device of the present invention, the first means e calculates the temporal change amount of the wheel speed difference between the right wheel and the left wheel based on the detected right wheel speed and left wheel speed, The second means f compares the change amount calculated by the first means e with a predetermined value, and when the change amount exceeds the predetermined value, the control device g causes the damping force of the shock absorber b to be large. A drive signal corresponding to the damping force switching member a is output so as to switch to the state.

Conventionally, it has been considered to detect the rolling state at the time of turning based on the steering angular velocity, which is the amount of change over time of the steering angle, and the vehicle speed, and perform damping force control.
For example, even if the steering angular velocity is the same and the vehicle speed is the same, the actual rolling state may change due to the influence of external disturbances such as side wind and frictional conditions on the road surface.

On the other hand, in the case of the shock absorber control device, the damping force control is performed using the temporal change amount of the wheel speed difference between the left and right wheels based on the information from the wheels that directly prosper the disturbance. Therefore, the rolling state change actually occurring in the vehicle can be reliably grasped as the yaw acceleration,
The state in which the rolling phenomenon is likely to occur can be detected quickly and surely, and the occurrence of the rolling phenomenon can be suppressed.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 9.

FIG. 2 is a block diagram showing the overall configuration of one embodiment.

In the figure, 1 is a microcomputer having a CPU 1-1, ROM 1-2 and RAM 1-3, 2 is a right front wheel speed sensor for detecting the wheel speed of the right front wheel of the vehicle, 3 is a left front wheel for detecting the wheel speed of the left front wheel Speed sensors 4, 5 are input buffers, 6 through 9 are shock absorbers provided for the respective four wheels of the vehicle, the damping force of which is adjusted in response to an electric signal, and 10 through 13 are Drive circuits for driving the shock absorbers 6 to 9, respectively, and 14 are key switches. It should be noted that it may be considered that the microcomputer 1, the input buffers 4 and 5, and the driving circuits 10 to 13 constitute the control device g according to the present invention.

The front right wheel speed sensor 2 has a shield plate, which is a rotating body attached to the front right wheel, and has a light-emitting diode and a phototransistor facing each other. Light is passed through and blocked from the phototransistor, and switching of the phototransistor generates a pulse signal having a frequency compared with the rotation speed of the right front wheel, that is, the wheel speed. The right front wheel speed sensor 2
In addition to the photoelectric conversion type as described above, an electromagnetic pickup or a reed switch may be used. The left front wheel speed sensor 3 also has the same configuration as the right front wheel speed sensor 2 and generates a pulse signal having a frequency proportional to the left front wheel speed. The pulse signal generated by the right front wheel speed sensor 2 and the pulse signal generated by the left front wheel speed sensor 3 are waveform-shaped and amplified by the input buffer 4 and the input buffer 5, respectively, and then the microcomputer 1
Entered in.

Each structure of the shock absorbers 6 to 9 is, for example, as schematically shown as a sectional view in FIG.

In FIG. 3, the drive circuit is provided above the upper movable part 20.
A coil 21 electrically connected to 10, 11, 12 or 13 and a ring-shaped core that is moved and held upward together with the connecting rod 22 by a magnetic force generated when the coil 21 is energized.
23 and are provided.

When the coil 21 is in the non-energized state, the flow control valve 24 at the tip of the connecting rod 22 and the piston 26 provided at the tip of the piston rod 25 are maintained in the state as shown in the drawing, and the first oil chamber 40 and The oil is allowed to flow relatively smoothly between the second oil chamber 50 and each other. In other words, the damping force of the shock absorber 6, 7, 8 or 9 is maintained at a normal level, that is, a low level. That is, the shock absorbers 6, 7, 8 or 9 are maintained as weak dampers.

On the other hand, when the coil 21 is energized by the drive circuit 10, 11, 12 or 13, the core 23 receives an upward force due to the generated magnetic force, and the connecting rod 22 moves upward together with the core 23,
Since the flow control valve 24 blocks the passage 28 that connects the first oil chamber 40 and the valve chamber 27, the flow resistance between the first oil chamber 40 and the second oil chamber 50 becomes a high level, and therefore the shock absorber. The damping force of 6, 7, 8 or 9 becomes higher. While the coil 21 is in the energized state, the flow control valve 24 is connected to the passage 28.
The damping force of the shock absorber 6, 7, 8 or 9 is increased, that is, the damping force is maintained to be a strong damper.

In this way, the shock absorbers 6 to 9 have large and small damping forces corresponding to the energization / de-energization of the coil 21, respectively. Coil 21, connecting rod 22, core 23, flow control valve
24, the piston 26 and the passage 28 correspond to the damping force switching member a according to the present invention.

After the key switch 14 is turned on, the microcomputer 1 executes the processing as schematically shown in FIG.

In this process, in step 101, the left front wheel speed V _FL is calculated from the pulse signal input from the left front wheel speed sensor 3 via the input buffer 5, and then in step 102, the right front wheel speed sensor 2 The front right wheel speed V _FR is calculated from the pulse signal input from the above through the input buffer 4.

Next, at step 103, the average value of both wheel speeds V _FL , V _FR , that is, the vehicle speed V is calculated from the calculated left front wheel speed V _FL and right front wheel speed V _FR .

Next, at step 104, a fifth step is performed with the vehicle speed V as a parameter.
A value α corresponding to the vehicle speed V at that time point on the _first damping force switching curve f ₁ (V) as shown in the figure is obtained. Where f
It can be considered that ₁ (V) corresponds to the limit curve of rolling phenomenon.

Next, at step 105, the difference V _LR between the above-calculated left front wheel speed V _FL and right front wheel speed V _FR is calculated.

Next, at step 106, the wheel speed difference V _LR and α are compared in magnitude.

When the wheel speed difference V _LR is less than α (however, when V _LR is negative and is greater than −α), that is, when it corresponds to a region other than the shaded region in FIG. 5, the damping force Since it is desirable that the vehicle is in a small state, the damping force is not switched to a large state, and then in step 107, the left front wheel speed V _FL
Difference between wheel speed V _FR and the front right wheel speed V _FR V _LR
The _LR / Delta] t, obtains a V _LR computed in step 105, the last, the difference between the computed V _'LR at step 105.

It may be considered that steps 105 and 107 correspond to the first means e in the present invention.

Next, in step 108, a sixth parameter is set with the vehicle speed V as a parameter.
A value β corresponding to the vehicle speed V at that time point on the _second damping force switching curve f ₂ (V) as shown in the figure is obtained. Here, β may be considered as a predetermined value in the present invention, and f ₂ (V) is the above f
Similar to ₁ (V), it may be considered as a limit curve for the occurrence of rolling phenomenon.

Next, at step 109, the change amount ΔV _LR / Δt and the predetermined value β are compared in magnitude. It may be considered that this step 109 corresponds to the second means f according to the present invention.

When the amount of change ΔV _LR / Δt is less than a predetermined value β (however, Δ
When V _LR / Δt is negative and is larger than −β, that is, when it corresponds to a region other than the shaded region in FIG. 6, it is desirable that the damping force is small. Is not switched to a large state, and then in step 110, the timer value T is decremented. The timer value T is set when the damping force is switched to a large state, and the set value is held while the large damping force is maintained.

If the timer value T is “0”, then step 112
At, processing for reducing the damping force is performed.
By this processing, the coils 21 of the shock absorbers 6 to 9 are de-energized via the drive circuits 10 to 13.
On the other hand, when the timer value T is not "0", the routine of FIG. 4 is exited without switching the damping force from the large state to the small state.

Thus, the absolute value of the wheel speed difference | V _LR | is less than the predetermined value α, and the absolute value of the change amount | ΔV _LR / Δt | is the predetermined value β
If less, the damping force is kept small.

After that, if the absolute value of the wheel temperature difference | V _LR | becomes a predetermined value α or more due to the vehicle entering a curve, or the absolute value of the change amount | ΔV _LR / Δt | becomes a predetermined value β or more. In new steps 113 and 114, processing for switching the damping force from a small state to a large state and processing for setting a predetermined value for the timer value T are performed. Here, the processing for switching the damping force to a large state is performed by the drive circuit 10 or
Coil 21 of shock absorber 6 or 9 via 13
Is a process of outputting a drive signal for energizing the.

After switching to a state in which the damping force is large in this way, the absolute value of the wheel speed difference | V _LR | is still the predetermined value α (however,
This value changes to a value corresponding to the vehicle speed thereafter. ) Or more, or the absolute value of the change amount | ΔV _LR /
Δt | is a predetermined value β (However, this value is the same as the above predetermined value α.
The value will depend on the vehicle speed thereafter. ) For a certain period of time, the damping force is kept large and the timer value T is kept at a predetermined value.

After that, (1) the absolute value of the wheel speed difference | V _LR | decreases to less than the predetermined value α, and the change amount at this time | ΔV _LR / Δ
t | is less than the predetermined value β, or (2) change amount | ΔV
_{When LR} / Δt | decreases and becomes less than the predetermined value β (assuming this time is t ₁ ), the timer value T is decremented, but at least the state of (1) or (2) above The timer value T is the value "0" unless it is continued for a time corresponding to the predetermined value of the timer value T (provisionally T ₀ ).
Is not decremented until, and therefore at least time point (t ₁
Since the processing of step 112 is executed only after + T ₀ ), the damping force is kept in a large state until this time (t ₁ + T ₀ ). This means that if the damping force is switched to the small state at the time point t ₁ , then the damping force becomes large when the vehicle is in a traveling state in which the damping force must be switched to the large state again after a short time. This is because it is considered that the driving feeling is likely to be hindered because the vehicle is switched from the small size to the large size immediately after the switching to the small size. Note that the state of (2) above includes a traveling state in which the vehicle travels in a curve such that the turning radii become equal after entering the curve.

When the timer value T becomes "0", a process for switching the damping force from large to small is executed in step 112,
The coil 21 is inverted to the non-energized state, and the damping force becomes small.

As described above, when the absolute value of wheel speed difference | V _LR | or the absolute value of change amount | ΔV _LR / Δt | when the vehicle enters a curve is equal to or greater than a predetermined value α or another predetermined value β, , The damping force can be switched from small to large. Here, since the predetermined values α and β are both given by the characteristics shown in FIGS. 5 and 6 with the vehicle speed V as a parameter, the larger the vehicle speed V, the smaller the value, and the smaller the damping force. The switch to large is accelerated. Therefore, it becomes possible to sufficiently suppress the rolling phenomenon that tends to occur as the vehicle speed V increases.

Further, even if a disturbance such as a side wind or a frictional condition on the road surface occurs, damping force control is performed using the temporal change amount of the left and right wheel speed difference based on the information from the wheel that directly reflects the influence of the disturbance. Therefore, the change in the rolling state actually occurring in the vehicle can be reliably grasped as the yaw acceleration, and the state in which the rolling phenomenon is likely to occur can be detected swiftly and surely, and the occurrence of the rolling phenomenon can be suppressed.

FIG. 7 is a flowchart showing the main processing part in the second embodiment of the present invention, which is a modification of step 109 in the flowchart of FIG. 4 showing the processing of the first embodiment as described above. Is. The other structure of the second embodiment is the same as that of the first embodiment.

The second embodiment is made for the purpose of solving the following problems remaining in the first embodiment as described above and performing better shock absorber control.

When the vehicle travels on a road α having a shape as shown in FIG. 9, for example, in a section A in which the vehicle travels straight until the vehicle enters a curve, a wheel speed difference V between the right wheel and the left wheel is V. The absolute value of the amount of change over time in _LR | ΔV _LR / Δt | is almost zero, and in section B immediately after the vehicle enters the curve, | ΔV _LR / Δt | increases and moves to a stable curve. At about the same time as | ΔV _LR / Δt | decreases, in the section C in which this stable curve traveling is performed, | ΔV _LR / Δt |
Takes a value near zero continuously, and when traveling in the section D near the end of the curve, | ΔV _LR / Δt | increases as at the time of entering the curve, and at the same time as leaving the curve | ΔV _LR / Δt |
Decreases, and | ΔV _LR / Δt | becomes substantially zero in the section E of straight traveling after exiting the curve.

Therefore, according to the first embodiment, the damping force may be switched from small to large in each of the section B and the section D.

However, since a rolling phenomenon is likely to occur when a vehicle enters a curve, it is appropriate to switch the damping force from small to large when a predetermined condition is satisfied when entering the curve. Since there is almost no possibility of rolling phenomenon when exiting the curve, the switching of the damping force from small to large when exiting the curve hinders the driving feeling.

Therefore, in this second embodiment, the absolute value of the change amount | ΔV _LR / Δt | and the predetermined value β are not simply compared in magnitude, but the curve entry and the curve exit are distinguished from each other. When escaping, the damping force is prohibited from switching from small to large. That is, as shown in FIG. 7, step 11 for performing processing for switching the damping force from small to large
The conditions for shifting to 3 are: (1) Wheel speed difference V _LR is 0k
m / h or more and the change amount ΔV _LR / Δt is a predetermined value β or more, in other words, at least when the steering is turned right from the neutral position, or (2) the wheel speed difference V _LR Is less than 0 km / h and the change amount ΔV _LR / Δt is less than or equal to a predetermined value −β, in other words, at least one of the case where the steering wheel is operated to the left from the neutral position is a condition, Therefore, when the operation of returning the steering wheel to the neutral position is performed, that is, when the vehicle exits the curve, the damping force is not switched from small to large because the transition to step 113 is prohibited.

Therefore, according to the second embodiment, when the vehicle is traveled such that the wheel speed difference V _LR changes with time as shown in the upper part of FIG. 8, the change amount ΔV _LR / Δt is equal to the intermediate part of FIG. The damping force changes as shown in the lower part of FIG. The broken line in the damping force change waveform represents the damping force change generated when the vehicle exits the curve, which is generated in the first embodiment, but according to the second embodiment, such a damping force change does not occur.

As described above, according to the present invention, the temporal change amount of the wheel speed difference between the right wheel and the left wheel is calculated, and when the change amount exceeds a predetermined value, the damping force is switched from small to large. As a yaw acceleration, the state where the rolling phenomenon is likely to occur at the start of turning corresponding to the disturbance received by the vehicle can be recognized quickly and surely, which can sufficiently suppress the rolling phenomenon and improve the driving feeling. it can.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is an overall configuration diagram of an embodiment of the present invention, FIG. 3 is a sectional view showing a schematic configuration of a shock absorber, and FIG. 4 is an outline of processing by a control device. FIG. 5 is a flow chart schematically showing the wheel speed difference V _LR.
And the vehicle speed V, the first damping force switching curve f ₁ (V) and the damping force, FIG. 6 shows the variation ΔV _LR / Δt, the vehicle speed V and the second damping force switching curve f ₂ (V) and a damping force relationship diagram, FIG. 7 is a flow chart showing the main part of the second embodiment, and FIG. 8 is a time chart for explaining the operation of the second embodiment. FIG. 9 shows an explanatory view for explaining the improvement points of the second embodiment. a ... Damping force switching member b ... Shock absorber c ... Right wheel speed sensor d ... Left wheel speed sensor e ... First means f ... Second means g ... Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Ishiguro, 1-1, Showa-machi, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Noriyuki Nakajima, 1-1, Showa-cho, Kariya city, Aichi prefecture Co., Ltd. (72) Inventor Kazuo Masaki 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. (72) Inventor, Motoharu Suzuki, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihondenso Co., Ltd. (56) References JP-A-58-116214 (JP, A) JP-A-58-167210 (JP, A) Actual development Sho-56-147107 (JP, U)

Claims (1)

[Claims] 1. A shock absorber control device for adjusting a damping force of a shock absorber that drives a damping force switching member according to a running state of a vehicle, wherein a right wheel speed sensor for detecting a speed of a right wheel and a speed of a left wheel. A left wheel speed sensor, first means for calculating a temporal change amount of a wheel speed difference between the right wheel and the left wheel based on the detected right wheel speed and left wheel speed, and the first means. And a second means for comparing the amount of change calculated by the means with a predetermined value. When the amount of change exceeds the predetermined value, the damping force switching member is adapted to switch to a large state of the damping force. A shock absorber control device, comprising: a control device that outputs a drive signal for controlling the shock absorber.